kris01

Ja333es display problem

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Hi

Today I received used JA333ES. It wasn't in original box.   When I removed it from a box i heard flying parts inside  the MD case. 

It must have been dropped although box wasn't damaged.

MD disc tray didn't open. Somehow I managed to repair MD disc tray and now it plays. I don't what could be wrong with the display.

I checked all connections but it seems all are firmly pluged. Leds on buttons are on.

Any ideas?

Chris

 

 

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What exactly is the problem with the display? Is it completely dark?

Several things can happen. The quickest checks, that don't need much testing gear:

- check if all those flat cables are seated properly
- check for any electronic components that look burnt , also, for dark brown or black spots/stains on the PCBs
- check if those tiny cathode filaments inside the VFD are not broken. Two photos below are from different models, but give you the idea

The left one shows intact filaments, the one on the right shows the topmost filament broken:

2269.jpg . 2210.jpg

 

 

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Flat cables seem to me that are properly pluged. 

I took a picture of display board and there is a dark area.

20170413_145727.jpg

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If you mean the brown stain around the pins of CN751, that is most probably some residue of the soldering flux (rosin). Not a problem normally.

How strong is your electronics vein? There are some test points that can be checked with a DMM, to see where the signal is lost.

But first, how about your display's cathode filaments?

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I am not good in electronics but I could try. I didn't remove the display so far  I was afraid not to damage it more.

I will check the display tomorrow.

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So I've checked the display and I think it is damaged. Dark area in the corner.  Tiny cathode filaments inside the VFD look good.

20170420_160305.jpg

20170420_161718.jpg

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7 hours ago, kris01 said:

So I've checked the display and I think it is damaged. Dark area in the corner.  Tiny cathode filaments inside the VFD look good.

That dark spot is all right. It is there on nearly all VFD-s - see my second photo above. Cathode filaments are OK, this is good news.

You may need to check the cathode voltage, and the VFD controller chip, whether or not it gets the proper supply voltages and signals (latter one would require an oscilloscope though).

If you don't feel comfortable with such measurements, I would suggest to stop here, and take the unit to a service. Without much experience, even a test tip put to a wrong position (say, accidentally shorting two pins) can cause further damage to the unit.

But one thing you can do without big risk: if you have a DMM, set it to AC Voltage, and measure the voltage across the VFD cathode, i.e., on your photo, the leftmost and the rightmost pins of the display. Those are both double pins, that means you can touch either one of a pair, but the best way is to point your probes between the twin pins, that can give you a relaxed, firm position to do the voltage check.

If you measure something like 3...5 Volts (AC), then the circuitry that drives the cathode is OK.

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The last thing I checked is this flat wire tape. Two left look suspiciously to me.

I don't feel confident with such things so I will look for service. If I don't find any I will try it on my own.

20170420_154535.jpgflat tape.jpg

 

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Not just suspect Kris - absolutely no good at all - need to replace or bypass

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9 hours ago, kris01 said:

The last thing I checked is this flat wire tape. Two left look suspiciously to me.

Yes, this cable looks broken, and most probably not only the two left lines - see how the whole thing is wrinkled. Bad handling for sure, for several times.

If you tell me which connector it is, I can check, whether or not it was the cause for the dark display.

And such a cable you can replace yourself easily. New cables are available on ebay for example. Just look for the proper pitch (inches or millimeters beetwen two lines), if you don't find a cable with the exact number of lines, buy a wider one, and cut the excess wires using a pair of scissors.

(There is a method of repairing such a broken cable, but it is kinda time consuming, plus requires thorough attention and an easy hand)

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I don't think that all lines in flat wire are broken because it also supplies LED on buttons and they are on. Maybe only one is broken just for the display.

After some investigation i noticed that LED on REC button it is not working, so you are probably right  flat wire could be the reason.

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I took a look at the schematic. The leftmost (topmost on the second photo) pin is for the -36V, that gives the cathode a negative charge (heating AC is delivered on pins 5 and 6). The Rec LED is driven from pin 24 (second from other end).

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I think left wire (topmost) is line number 25 and is NC (not connected?). Line 24 and line 25 on photo looks like damaged. I will look for new flat wire.

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11 hours ago, kris01 said:

I think left wire (topmost) is line number 25 and is NC (not connected?). Line 24 and line 25 on photo looks like damaged.

That's right - seems both edges of the cable are damaged.

Yes, NC stands for "not connected".

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Something like this?

http://www.ebay.ca/itm/5pcs-FFC-FPC-26-pin-0-5mm-Pitch-Ribbon-Flat-Cable-Wire-ZIF-HDD-20cm-Long-New-/171907590525

Or you could take a 50pin and cut down the middle. Gyula?

I'm sure the major houses (Mouser, etc) will handle exactly the right one.

Is this the right one? (not sure about the pitch which on this available part is .5 mm). It's called an FFC "Flat Face Cable".

http://www.mouser.com/search/ProductDetail.aspx?R=0virtualkey0virtualkey15020-0955

Now you have to find one, instead of 2000.

Maybe this? Still not sure about that pitch parameter...

http://cpc.farnell.com/molex/15015-0425/jumper-cable-ffc-0-3mm-101-6mm/dp/CN18201

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4 hours ago, sfbp said:

Something like this?

http://www.ebay.ca/itm/5pcs-FFC-FPC-26-pin-0-5mm-Pitch-Ribbon-Flat-Cable-Wire-ZIF-HDD-20cm-Long-New-/171907590525

Or you could take a 50pin and cut down the middle. Gyula?

Yes, 0.5mm pitch 50 pin can make it in a 1mm pitch 25 pin socket.

I found this, but looks tooo long: here. But that guy has other width/length, may be worth asking.

 

What is the length of your cable, Chris? I can also check my spares box.

And whether or not is it an inverted cable (contacts on one end are on the back side of the ribbon).

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I've just found and ordered two pieces, just in case. Close area to me so I hope to get it next week.

275 mm wouldn't be too long? 125 mm is enough.

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4 hours ago, kris01 said:

275 mm wouldn't be too long? 125 mm is enough.

Sounds a bit long. It is not a problem from resistance point of view, however, long cables can pick up electromagnetic noise, like an aerial.

What you can do though is to fold the cable in Z or Omega shape, making sure the folded parts cover each other precisely - in other words, wires won't get over a neighbouring one, to avoid interference. And no need for very sharp edges, to avoid cracks.

In your case  keeping the 125 mm distance beetween the two ends you first make a fold at ~100mm, then at ~75mm from the first one, making the Z. In the middle you will have triple layers, consuming about 225mm of the length, plus ~25-25mm-s at the ends

Once this is done, you may want to tie it together with a piece of adhesive tape.

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Kris - If the one you ordered does not fit - then message me - I have spare units that I can strip for one - you are welcome to it if I can help.

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I expect to get it tomorrow so it explain if it is display or wire problem.

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Good news. It works, it does!!!. It wouldn't be possible without your help. Thank you very much!!!.

20170425_115258.jpg

20170425_122838.jpg

20170425_130717.jpg

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That's great news Kris - a fine achievement - time now to relax and enjoy!

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Great work Kris. Always good to see a machine saved, especially one as nice as that. 

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